The field of the invention is broadly sporting goods and more particularly to water borne sporting goods, such as surfboards, wind surfers, wake boards and sailboats.
Typically, surfboards are made utilizing a urethane foam core. The foam core is shaped to the desired shape. The core is then covered with a composite material which is cured, smoothed and polished.
Various alternative designs have been proposed and used. A recreational board having a honeycomb core is shown in U.S. Pat. No 5,514,017. The honeycomb core is surrounded by a fiberglass scrim and with a second laminating layer.
Another recreational board is shown in U.S. Pat. No. 5,266,249. This board is formed by placing honeycomb core laminates in a mold and placing a vacuum bag inside the hollow structure. The vacuum bag pulls the honeycomb core laminate against the mold while it is cured. The vacuum bag is then removed through a hole in the hollow member. The hollow member has an inner support wall, which also has a honeycomb core surrounded by composite material layers.
An expanded polystyrene filled board is commercially available under the trademark xe2x80x9cTuflites.xe2x80x9d The expanded polystyrene blank of this board is formed in a mold. The blank is then surrounded by a sandwiched laminate containing a PVC sheet foam.
While the present invention is useful for a number of recreational boards, such as wind surfers and wake surfing boards, it is known to be more challenging to make a surfboard, since a surfboard must flex a desired amount and in desired locations. In the present foam shaping process, the foam core is shaped to create the desired flexibility. To date, no other board forming process has resulted in the desired flexibility present in conventionally shaped boards.
It is an object of the present invention to make a hollow surfboard which will flex in an amount and at locations desired by surfers.
The present invention is for a surf board having a deck and a bottom. In one aspect, an embodiment has a deck fabricated from a laminate having an outer composite layer, an intermediate core fabricated from a honeycomb material, and an inner composite layer under the honeycomb material. The deck portion is joined to a bottom portion also fabricated from a laminate having an outer composite layer, a honeycomb inner core, and a bottom composite layer. A stringer comprising an elongated member is adhered to the inner surfaces of the deck and bottom. The core does not extend either to a nose or a tail of the surfboard so that the nose and tail are more flexible than that portion of the surfboard containing the elongated stringer. In another aspect, the stringer has a layer of urethane foam between its lower surface and the inner surface of the bottom to provide a degree of flexibility. Preferably, the stringer is about half the length of the surfboard and is positioned longitudinally and closer to the tail than to the nose.
The present invention also is for the process of forming the above-described surfboard. The process includes the steps of forming a first layer of honeycomb core into the shape of a deck of a surfboard. The core is covered top and bottom with resin and fiber, which extends past the outer peripheral edge of the honeycomb core. This deck laminate is placed on a shaped concave deck mold and surrounded with a vacuum bag. The vacuum bag pulls the laminate against the mold after which it is heated and the laminate cured. The bottom is formed utilizing the same steps. After curing, a stringer is adhered longitudinally to the inner surface of the deck or bottom. Next, an adhesive composition is placed on the exposed side of the stringer and the deck and bottom pieces are joined around the outer flaps thereof and cured to form the assembly into a hollow surfboard having a longitudinal stringer. Preferably, the adhesive composition which is placed on the stringer after it has been adhered to one of the surfaces, is a urethane prefoam which rises and forms a bond between the stringer and the inner surface of the board half to which it is adhered.